OAHelper Topics
Practice coding questions by topic.
Build depth in the topics that appear repeatedly across real online assessments: arrays, graphs, dynamic programming, strings, trees, SQL, heaps, and more.
Array
2609 real OA questions
Math
1423 real OA questions
Greedy
1258 real OA questions
String
1219 real OA questions
Simulation
1145 real OA questions
Sorting
1100 real OA questions
Hash Table
889 real OA questions
Dynamic Programming
847 real OA questions
Aptitude
616 real OA questions
Counting
592 real OA questions
Prefix Sum
551 real OA questions
Binary Search
451 real OA questions
Two Pointers
408 real OA questions
Depth-First Search
376 real OA questions
Graph Theory
372 real OA questions
Matrix
339 real OA questions
Tree
330 real OA questions
Breadth-First Search
303 real OA questions
Bit Manipulation
285 real OA questions
Enumeration
266 real OA questions
Number Theory
261 real OA questions
Logical Reasoning
255 real OA questions
Heap (Priority Queue)
250 real OA questions
Sliding Window
237 real OA questions
Combinatorics
224 real OA questions
Graph
224 real OA questions
Verbal Ability
180 real OA questions
SQL
169 real OA questions
Design
168 real OA questions
Stack
159 real OA questions
Shortest Path
149 real OA questions
Data Interpretation
128 real OA questions
Database
109 real OA questions
Recursion
109 real OA questions
Binary Tree
96 real OA questions
Python
93 real OA questions
Data Structures
91 real OA questions
Percentages
91 real OA questions
Quantitative Aptitude
86 real OA questions
Queue
86 real OA questions
Backtracking
82 real OA questions
Union-Find
80 real OA questions
Monotonic Stack
78 real OA questions
Union Find
78 real OA questions
Binary Indexed Tree
73 real OA questions
String Matching
72 real OA questions
Segment Tree
71 real OA questions
Mechanical Engineering
69 real OA questions
Geometry
67 real OA questions
Memoization
65 real OA questions
aptitude
63 real OA questions
Linked List
61 real OA questions
greedy
61 real OA questions
Ordered Set
58 real OA questions
Arithmetic
56 real OA questions
Probability
56 real OA questions
array
56 real OA questions
math
56 real OA questions
Machine Learning
54 real OA questions
Bitmask
52 real OA questions
simulation
48 real OA questions
Grammar
47 real OA questions
Java
47 real OA questions
Ratio and Proportion
46 real OA questions
dynamic-programming
46 real OA questions
Aggregation
44 real OA questions
string
44 real OA questions
Topological Sort
42 real OA questions
Brainteaser
38 real OA questions
sorting
37 real OA questions
Minimum Spanning Tree
35 real OA questions
Algorithms
34 real OA questions
MCQ
34 real OA questions
Operating Systems
33 real OA questions
Pointers
33 real OA questions
Sweep Line
33 real OA questions
Trie
33 real OA questions
C
32 real OA questions
Statistics
32 real OA questions
hash-table
32 real OA questions
Averages
31 real OA questions
Monotonic Queue
31 real OA questions
Reading Comprehension
31 real OA questions
arrays
31 real OA questions
counting
31 real OA questions
logical-reasoning
31 real OA questions
Computer Networks
30 real OA questions
Binary Search Tree
29 real OA questions
Computer Architecture
29 real OA questions
Divide and Conquer
29 real OA questions
C Programming
28 real OA questions
Puzzles
28 real OA questions
Vocabulary
28 real OA questions
Time and Work
27 real OA questions
Critical Reasoning
26 real OA questions
Join
26 real OA questions
Operators
26 real OA questions
Seating Arrangement
26 real OA questions
Linear Equations
25 real OA questions
OOP
25 real OA questions
Algebra
24 real OA questions
C++
24 real OA questions
Output Prediction
24 real OA questions
implementation
24 real OA questions
Arrays
23 real OA questions
Oracle
23 real OA questions
Coding-Decoding
22 real OA questions
English
22 real OA questions
Group By
22 real OA questions
Profit and Loss
22 real OA questions
verbal-ability
22 real OA questions
DBMS
21 real OA questions
Game Theory
21 real OA questions
System Design
21 real OA questions
Attention to Detail
20 real OA questions
Doubly-Linked List
20 real OA questions
Flowchart
20 real OA questions
strings
20 real OA questions
Implementation
19 real OA questions
OOPS
19 real OA questions